examples(fetch-rs): Harden fetch tool: add env-configurable options, enforce URL scheme & redirect loop detection, improve decoding & error reporting

[Mossaka]

Signed-off-by: Jiaxiao Zhou [email protected]

[Copilot]

Pull Request Overview

This PR significantly enhances the fetch-rs tool by adding comprehensive error handling, environment-configurable options, URL scheme validation, redirect management, and improved content decoding. The changes transform the simple fetch tool into a robust HTTP client with production-ready features.

• Adds environment-configurable options for limits (redirects, body size), timeout, and user agent
• Implements URL scheme validation, redirect loop detection, and comprehensive error handling
• Introduces content decoding support for gzip, deflate, and brotli compression with detailed response metadata

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 4 comments.

File	Description
examples/fetch-rs/src/lib.rs	Complete rewrite adding structured error handling, redirect management, content decoding, and environment configuration
examples/fetch-rs/Cargo.toml	Adds new dependencies for compression, URL parsing, MIME type handling, and removes scraper

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[Copilot]

The timeout check occurs after the request completes and body is processed, making it ineffective. The timeout should be enforced during the HTTP request itself, not after completion.

[Copilot]

The reason for reversing the encoding order should be documented. HTTP content-encoding headers list encodings in the order they were applied, so they must be decoded in reverse order.

Suggested change

	// HTTP content-encoding headers list encodings in the order they were applied,
	// so they must be decoded in reverse order.

[Copilot]

The function always clones the data even when no clipping is needed. Consider returning a slice reference when not truncated to avoid unnecessary allocation.

[Copilot]

The iterator chain could be simplified using find() instead of skip_while().next() for better readability and potentially better performance.

Suggested change

	.skip_while(|b| b.is_ascii_whitespace())
	.next()
	.find(|b| !b.is_ascii_whitespace())

[Mossaka]

@copilot open a new pull request to apply changes based on the comments in this thread and fix this test failure:

Error: Timeout waiting for tool list change notification

Caused by:
    deadline has elapsed

Stack backtrace:
   0: <E as anyhow::context::ext::StdError>::ext_context
test test_tool_list_notification ... FAILED
   1: anyhow::context::<impl anyhow::Context<T,E> for core::result::Result<T,E>>::context
   2: transport_integration_test::test_tool_list_notification::{{closure}}
   3: <core::pin::Pin<P> as core::future::future::Future>::poll
   4: <core::pin::Pin<P> as core::future::future::Future>::poll
   5: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}::{{closure}}::{{closure}}
   6: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}::{{closure}}
   7: tokio::runtime::scheduler::current_thread::Context::enter
   8: tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}
   9: tokio::runtime::scheduler::current_thread::CoreGuard::enter::{{closure}}
  10: tokio::runtime::context::scoped::Scoped<T>::set
  11: tokio::runtime::context::set_scheduler::{{closure}}
  12: std::thread::local::LocalKey<T>::try_with
  13: std::thread::local::LocalKey<T>::with
  14: tokio::runtime::context::set_scheduler
  15: tokio::runtime::scheduler::current_thread::CoreGuard::enter
  16: tokio::runtime::scheduler::current_thread::CoreGuard::block_on
  17: tokio::runtime::scheduler::current_thread::CurrentThread::block_on::{{closure}}
  18: tokio::runtime::context::runtime::enter_runtime
  19: tokio::runtime::scheduler::current_thread::CurrentThread::block_on
  20: tokio::runtime::runtime::Runtime::block_on_inner
  21: tokio::runtime::runtime::Runtime::block_on
  22: transport_integration_test::test_tool_list_notification
  23: transport_integration_test::test_tool_list_notification::{{closure}}
  24: core::ops::function::FnOnce::call_once
  25: test::__rust_begin_short_backtrace
  26: test::run_test::{{closure}}
  27: std::sys::backtrace::__rust_begin_short_backtrace
  28: core::ops::function::FnOnce::call_once{{vtable.shim}}
  29: std::sys::pal::unix::thread::Thread::new::thread_start
  30: <unknown>
  31: <unknown>
2025-10-04T00:25:12.836547Z  INFO load_component{uri="file:///home/runner/work/wassette/wassette/examples/fetch-rs/target/wasm32-wasip2/release/fetch2.wasm"}: wassette: Saved precompiled component component_id=fetch2
2025-10-04T00:25:12.838490Z  INFO load_component{uri="file:///home/runner/work/wassette/wassette/examples/fetch-rs/target/wasm32-wasip2/release/fetch2.wasm"}: wassette: Saved component metadata component_id=fetch2
2025-10-04T00:25:12.839200Z  INFO load_component{uri="file:///home/runner/work/wassette/wassette/examples/fetch-rs/target/wasm32-wasip2/release/fetch2.wasm"}: wassette: Successfully loaded component component_id=fetch2 status=New tools=["fetch"]
test test_fetch_component_workflow ... ok

failures:

failures:
    test_tool_list_notification

[Mossaka]

@copilot open a new pull request to apply changes based on the comments in this thread